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This research paper presents systematic micromagnetic modeling of dynamic spin solitons carried by perpendicular magnetization component on a topologically preserved chiral sequence of uniform 360° in-plane domain walls with fixed boundaries in a strip. The long, narrow strip of a soft, magnetic thin film has a repeated in-plane magnetization pattern such that the local magnetization will rotate uniformly in a single chirality, either clockwise or counterclockwise, when moving along the strip in one direction at a constant speed. As spins in an excited soliton precess around its local magnetization field, the exchange interaction with the underlying chiral magnetization configuration yields a linear soliton motion with the direction determined by the handedness of precession and the underlying magnetization chirality. The local hyperbolic secant-like soliton profile holds its shape and energy when traveling without damping, continually changes its shape, and decays otherwise. [ABSTRACT FROM AUTHOR]

Utilizing micromagnetic modeling, we have explained the unprobed characteristics of 360° full cycle in-plane magnetization rotation and the resulting propagation of a magnetization wave along a ferromagnet nanowire. The magnetization wave, which is generated by setting off spin oscillation at one end of a ferromagnetic strip, propagates till the end of the wire. A perpendicular spin torque oscillator (STO) could generate magnetization rotation at one end of the ferromagnetic strip that is also part of the STO. Our results demonstrate that the oscillation frequency of the spins along the wire maintains excellent fidelity while the spatial wavelength of the magnetic wave increases. The driving mechanism behind the propagation of the wave is found to be exchange-springs, which enables the propagation of the wave without the need for a 'carrier' force, such as spin-transfer torque (STT) or spin Hall effect (SHE). Furthermore, we demonstrate that the gradient of the exchange energy drives the magnetic wave forward, while the in and out of plane anisotropy fields govern the shape of spin oscillation trajectories along the wire. Additionally, we show that stopping the oscillation at the STO end causes the wave to cease propagation after relaxation, and altering the STO rotational chirality leads to merging and annihilating domain walls of opposite winding numbers. [ABSTRACT FROM AUTHOR]

Utilizing micromagnetic modeling, we have explained the unprobed characteristics of 360° full cycle in-plane magnetization rotation and the resulting propagation of a magnetization wave along a ferromagnet nanowire. The magnetization wave, which is generated by setting off spin oscillation at one end of a ferromagnetic strip, propagates till the end of the wire. A perpendicular spin torque oscillator (STO) could generate magnetization rotation at one end of the ferromagnetic strip that is also part of the STO. Our results demonstrate that the oscillation frequency of the spins along the wire maintains excellent fidelity while the spatial wavelength of the magnetic wave increases. The driving mechanism behind the propagation of the wave is found to be exchange-springs, which enables the propagation of the wave without the need for a 'carrier' force, such as spin-transfer torque (STT) or spin Hall effect (SHE). Furthermore, we demonstrate that the gradient of the exchange energy drives the magnetic wave forward, while the in and out of plane anisotropy fields govern the shape of spin oscillation trajectories along the wire. Additionally, we show that stopping the oscillation at the STO end causes the wave to cease propagation after relaxation, and altering the STO rotational chirality leads to merging and annihilating domain walls of opposite winding numbers. [ABSTRACT FROM AUTHOR]

In this article, we present a systematic study of using a machine learning (ML) data detection channel consisting of a convolutional neural network (CNN) for data recovery in a two-dimensional magnetic recording (TDMR) setting with two displaced readers. To mimic the actual head skew angle change over the entire disk platter, data recovery over a wide range of inter-track interference (ITI) has been investigated. During training, the CNN-based ML channel only “learns” to detect the main track data although the sampled input signals from both readers are taken as input. It is found that with reasonable training, the ML channel can almost completely eliminate the ITI-caused degradation of bit error rate (BER). Moreover, it is also found that the training processes are only needed at very few head skewing angles, adding to the viability of the possible practical implementation. We believe the understanding elucidated in this article could serve the basis for developing viable and robust ML-based data detection channels leading to significant areal density gain for TDMR technology. [ABSTRACT FROM AUTHOR]

In this article, we present a novel micromagnetic model for L10 ordered FePt grains based on their atomic structure. In this model, each monolayer of Fe atoms is represented by a magnetic moment vector and the entire grain consists of a stack of magnetic moments coupled by magnetostatic and nearest-neighbor exchange fields. The grain model enables simulation of incoherent magnetization switching, especially near the Curie temperature. The model is applied to simulate the heat-assisted recording process in granular L10 FePt thin-film media. One of the unique findings is that grains at transition centers could have a domain wall trapped within, provided sufficient grain height. The existence of these grains, whose magnetic moments could be fractional at transition centers, resulting in significant reduction of medium noise. The noise reduction is effectively equivalent to an increase of the number of grains across the read track width. Enhancing and controlling this mechanism by material engineering could lead to significant increase of area density capability, specifically, increase of track density, without decreasing grain size. [ABSTRACT FROM AUTHOR]

Convolution neural network (CNN) is used as the data detection channel for two-dimensional magnetic recording (TDMR). We demonstrate that by only feeding interfered multireader signals as well as the target binary data at supervised learning, it is possible for CNN to automatically resolve the intertrack interference (ITI) in a noisy environment without any physical modeling. It is worth mentioning that throughout the entire training/learning process, CNN never receives ITI-free waveforms as target nor is explicitly “instructed” to resolve ITI. We illustrate that the nonlinear detection capability plays the most important role for CNN to effectively “learn” the right correlation between multiple read channels under heavy noise. Therefore, ITI can be completely eliminated as long as the noise exhibits similar correlation, while the white electronic noise completely disturbs this correlation and “decorrelates” the channels, hence posing most serious limitations toward ITI mitigation capability for CNN. [ABSTRACT FROM AUTHOR]

In this article, we present a systematic modeling investigation for some important physical insights in microwave-assisted magnetic recording (MAMR). Specifically, the characteristics of the effective write field in the presence of the ac field generated by the embedded spin torque oscillator (STO) is analyzed in terms of field strength and field-gradient gain for recording, as well as the enhancement of reverse erasure field. It is found that the rotating frequency of the field generating layer (FGL) of the STO plays a very important role. The effective write field enhancement for both recording and erasure due to the rotating ac field increase with increasing the ac field frequency with a rate close to 1 T per 28 GHz. Either the recording field gain or erasure field enhancement rolls off at high frequencies. The roll-off frequency for the recording field gain is significantly higher, approximately 20 GHz, than that for erasure field enhancement, leaving a broader frequency range for the ac field over which substantial gains for the recording field strength and gradients can be obtained while avoiding any erasure field enhancement. The understanding also provides guidelines for both head and media designing. [ABSTRACT FROM AUTHOR]

Advances in microelectronics technology strongly depend on the thermal optimization of metal/dielectric interfaces, which requires precise modeling and thermal characterization of metal/dielectric structures. This work experimentally investigated the influence of metallic layers on the thermal boundary resistance of silicon nitride dielectric material. The results reveal that the thermal boundary resistance of silicon nitride thin films depends on the metallic layers. The thermal boundary resistance at the interface between Au and SiNx is larger than that between Co0.9Fe0.1 and SiNx. The reasons to cause this difference are discussed with phonon transmission probability and the ratio of the Debye temperature between metals and dielectrics. [ABSTRACT FROM AUTHOR]

In this paper, we present the vertical magnetoresistive random access memory (VMRAM) design based on micromagnetic simulation analysis. The design utilizes the vertical giant magnetoresistive effect of the magnetic multilayer. By making the memory element into a ring-shaped magnetic multilayer stack with orthogonal paired word lines, magnetic switching of the memory device becomes very robust. The design also adopts the readback scheme in pseudo spin valve MRAM so that only one transistor is needed for each bit line which can connect hundreds of memory elements, yielding a very high area density. It is estimated that the ultimate area density for the VMRAM is 400 Gbits/in.2. It is suggested that this memory design has the potential to not only replace the present semiconductor memory devices, such as FLASH, but also the potential to replace DRAM, SRAM, and even disk drives. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Perpendicularly spin-polarized current in the antiferromagnetic thin-film layer can generate in-plane spin precession. Incorporating this mechanism, a thin-film stack including a layer of antiferromagnetic material is added to the conventional spin-transfer torque (STT) magnetoresistive memory element to generate an additional rotating STT on the free/storage layer. With the chirality and frequency of the rotating STT matching the ferromagnetic resonance condition of the free layer, the switching current threshold, particularly for the switching from parallel to antiparallel states, can be significantly reduced. [ABSTRACT FROM AUTHOR]

A previous theoretical study has shown that spin-polarized current can excite ultra-high frequency spin precessions in collinear antiferromagnetic (AF) films due to the strong antiferromagnetic coupling with the frequency spanning over a wide spectrum from giga-hertz to tera-hertz. In this paper, we present a design to incorporate the AF-based spin torque oscillator into a conventional spin transfer torque magnetic random-access memory. The AF-based oscillator consists of a perpendicular spin polarization layer and an AF layer, separated by a normal metallic interlayer. The AF layer is then exchange-coupled to the free layer on the side that is opposite to the tunnel barrier of the magnetic tunnel junction. Magnetization of the perpendicular spin polarization layer always orients in the opposite direction to that of the reference layer on the other side of the tunnel barrier. When the AF layer thickness and materials are adequately designed, the lateral spin precession in the AF layer excited by the write current provides significant assistance to the magnetization switching of the free layer, resulting in substantial reduction of the switching current threshold and the switching time. [ABSTRACT FROM AUTHOR]

The Curie temperature distribution induced from grain size variation in heat-assisted magnetic recording (HAMR) can be alleviated by including the thermally insulating magnetic grain boundaries. In this paper, we present a systematic micromagnetic study on this new type of HAMR media, focusing on the impact to the recording behaviors from the exchange coupled magnetic boundary (shell). It is found that the soft magnetic shell of higher Curie temperature is capable of assisting the switching of FePt grain in both magnetization and transition process. The important implication of the proposed media for practical HAMR recording is that optimal performance now can be accomplished with relaxed recording conditions in both head field intensity and the heating source, eventually enhancing area density capability and the overall HAMR system stability. [ABSTRACT FROM AUTHOR]

Presents a study that examined the magnetization reversal in longitudinal and perpendicular thin films via computer simulation. Analysis of the collective micromagnetic processes; Cause of the reversal; Effect of the collective formation of vortices.

Presents a study which investigated the magnetization reversal processes in CoCr perpendicular thin films. Theoretical model and calculation method; Results and discussion; Conclusions.

Presents information on a study which developed a computer simulation model to conduct micromagnetic analysis of thin magnetic films. Methodology of the study; Results and discussion; Conclusion.

Presents a study on the micromagnetics of exchange biased Permalloy films. Use of combined magnetic force microscopy and micromagnetic modeling simulation; Lithographical patterning of bilayer films.

Introduces a parameter to describe the effectiveness of the exchange coupling and coercivity of antiferromagnetic materials. Fabrication of nickel-oxygen/nickel-iron bilayers; Effects of surface/interface roughness on exchange coupling and coercivity of the bilayers; Insensitivity of Hex to the texture of nickel-oxygen films.

In order to improve the recording efficiency in current perpendicular recording media, it is important to reduce the distance from the head to soft underlayer. In this paper, a soft magnetic intermediate layer is proposed to partially replace the presently used Ru intermediate layer. The new soft magnetic intermediate layer serves two purposes, which are as follows: (1) to decrease the thickness of the nonmagnetic Ru intermediate layer by providing a proper crystalline texture and surface morphology for the optimal crystalline grain growth of the magnetic storage layer on top and (2) to act as an additional soft magnetic underlayer that is closer to the head air bearing surface to enhance the recording performance. The prototypes of the soft magnetic intermediate layer consists of CoIr:SiO2/CoPt:SiO2/NiW multilayer structure. CoIr and CoPt were chosen because both have the hcp structure but the opposite sign for K1. A zero effective magnetoanisotropy of a composite grain is accomplished by varying the thickness ratio of each layer of CoIr and CoPt. The developed multilayer film shows the hcp (00.2) orientation with a dome morphology for facilitating the growth of the top magnetic storage layer as well as soft magnetic properties (K1=6.8×105 erg/cc). [ABSTRACT FROM AUTHOR]

Two-port network analysis is used to probe the dynamics of the perpendicular recording head. Two identical heads are aligned to each other with poletip to poletip on their air-bearing-surface sides, while the spacing is about the typical flying height. With two-port network analysis, forward transmission coefficient measurement shows the nonuniformity of the frequency response across the footprint of the poletip. It is suggested that the spatial distribution of the fast-field pulse can be optimized by constructing the fast write pulse with proper frequency components. In addition, the head-to-media recording performance is characterized by contact scanning recording tester. A single 0.15 ns/50 mA current pulse is good enough to complete the recording. [ABSTRACT FROM AUTHOR]

For discrete track media to become a viable alternative, it is essential to produce accurate servo patterns in a cost effective manner. This study presents a spin stand analysis and comparison of position error signals generated from various lithographically defined servo patterns and servo bursts written on continuous regions of the same perpendicular recording media. It is demonstrated that the edge variation on the patterned servo elements is much less than that found on conventional servo bursts. In addition, evidence shows that despite some amplitude loss resulting from the removal of magnetic material, patterned servo bursts produce good quality position error signals when compared to servo bursts written on continuous media. [ABSTRACT FROM AUTHOR]

Using micromagnetic modeling, the recording performance of exchange coupled composite (ECC) media with perpendicular heads was systematically studied. The simulations indicated that the switching field angular dependency of ECC media is similar to the continuous media switching behavior. By tuning the magnetic properties of the soft/hard layers, it was found that a soft layer with high saturation magnetization and low anisotropy energy caused large dc noise and unfavorable Adjacent Track Erasure (ATE) performance in recording, which is mainly due to the small nucleation field. A quantitative optimization of ECC media was given. Recording with different head designs on ECC media was also evaluated and this showed that large head field gradients at both the trailing edge and track edges are crucial to the implementation of ECC media at high recording areal density. [ABSTRACT FROM AUTHOR]

CoCrPt–SiO2 films for use as thin film tape media have been investigated. Bias sputtering and high Ar pressure were utilized to achieve desirable media properties (good in-plane orientation and enhanced grain decoupling) in these media. The in-plane orientation of the bias sputtered CoCrPt–SiO2 magnetic layer was well maintained even at a high content of SiO2 as Ru was used as an underlayer and deposited at high Ar pressure. Films of (10.0) textured CoCrPt–SiO2 on a Ru underlayer showed a large in-plane coercivity of 4000 Oe and transmission electron microscopy revealed an average grain size of about 10 nm, well decoupled by the oxide. The in-plane coercivity was a strong function of the Ru thickness. [ABSTRACT FROM AUTHOR]

In this paper, we present a methodology of segmented media stack design for microwave assisted magnetic recording. Through micro-magnetic modeling, it is demonstrated that an optimized media segmentation is able to yield high signal-to-noise ratio even with limited ac field power. With proper segmentation, the ac field power could be utilized more efficiently and this can alleviate the requirement for medium damping which has been previously considered a critical limitation. The micro-magnetic modeling also shows that with segmentation optimization, recording signal-to-noise ratio can have very little dependence on damping for different recording linear densities. [ABSTRACT FROM AUTHOR]

In this paper, we present systematic micromagnetic modeling investigation on recording process of segmented thin-film media with circularly polarized magnetic field at microwave frequencies. This paper provides insightful understanding about the segmented medium stack design in microwave-assisted magnetic recording (MAMR) by exploring the impact of signal-to-noise (SNR) ratio and recording track width. By utilizing segmentation of grains with exchange breaking layers, the ac magnetic field generated from spin torque oscillator can be best exploited. Via optimized medium stack design, MAMR is able to achieve both high SNR and areal density gain with the proposed notched-structure medium (top and bottom segments have the strongest crystalline anisotropy) compared with conventional graded medium (with gradually increasing anisotropy from top to bottom). By tuning crystalline anisotropy strength in top and bottom segment, we studied the MAMR behavior of SNR and track width under different ac frequencies. This provides a novel view for future segmented media design. [ABSTRACT FROM AUTHOR]

In designing the shape of magnetic random access memory elements, a sufficient difference in switching current threshold between a full-select element and a half-select memory element is critical. In this article, we present a systematic micromagnetic study of the margin of switching threshold for two specific shapes: eye shaped and ellipse. It is found that at small magnetic thickness, the eye-shaped element exhibits a higher switching threshold margin than the ellipse. However, for relatively thick storage layers, the opposite becomes true. The switching threshold is also a strong function of the initial magnetization state for the ellipse. [ABSTRACT FROM AUTHOR]

Magnetization dynamics during field reversal in thin film recording heads are studied via micromagnetic modeling. It is found that head field reversal under the current field can be characterized by two stages: an initial stage that is mainly governed by the gyromagnetic motion and virtually independent of energy damping, followed by a damping stage that strongly depends on the energy damping constant. Due to the finite energy damping in practical recording heads, the head field amplitude will roll off at high recording frequencies. Simply decreasing the current rise time or increasing current amplitude will not alleviate the situation, but rather worsen it. There exists an optimum current rise time at which the head field rise time is minimized and the roll-off frequency is maximized. [ABSTRACT FROM AUTHOR]

Thermally excited ferromagnetic resonance (TEFMR) in a spin valve head gives rise to mag-noise while its power spectral density directly reflects the magnetic field distribution in the sensing layer as well as the corresponding micromagnetic states. In this article, we report an experimental study on utilization of TEFMR spectral characteristics for spin valve head diagnosis and characterization. The study suggests that the variation of the micromagnetic states in the PM layer at the junctions is one of the most important factors causing the head-to-head variations of the recording performance, especially the heads from the same wafer. [ABSTRACT FROM AUTHOR]

A perpendicular write head with a stitched pole tip and side yoke recessed from the air-bearing surface is proposed and investigated using three-dimensional micromagnetic modeling. The design yields an increase of head field magnitude by 30% over the conventional single pole head. It is found that the optimal flare angle at the bottom of the yoke is 45°, for maximizing the on-track field magnitude and getting the minimum off-track field at the same time. Reducing the throat height significantly increases on-track field, while the off-track field increases as well. Lamination of the pole tip is necessary for producing robust zero remanent field for deep-submicron track widths. Introducing adequate transverse anisotropy in the head will significantly shorten the relaxation time of the magnetic moments after writing with little degradation on write efficiency. [ABSTRACT FROM AUTHOR]

A modified tilted perpendicular medium has been proposed. With crystalline easy axes oriented randomly at ±45° relative to the perpendicular direction in the cross-track plane, the in-plane magnetic charges in the uniformly tilted perpendicular media can be effectively eliminated. Recording properties of the tilted perpendicular media are studied via micromagnetic simulation. In addition to the advantage of less saturation field, titled perpendicular media also show improved recording performance as compared to the conventional perpendicular media. [ABSTRACT FROM AUTHOR]

A three-dimensional micromagnetic model has been developed to study single pole write heads with soft magnetic underlayer (SUL) for perpendicular recording at extremely small track widths. The study points out that at any practical ABS-to-SUL spacing, the maximum head field within the recording media at deep submicron track width and pole-tip thickness becomes significantly smaller than the ideal value of 4πM[sub s]. Head field gradient in the medium also degrades with decreasing track width. Maintaining the conventional design, a significantly large remanent head field develops for track width below 100 nm, presenting danger of erasing previously recorded bits. The origin of the large remanent head field is the failure for a pole tip to reach a completely demagnetized state due to the overwhelming ferromagnetic exchange energy at the deep submicron pole-tip dimensions. [ABSTRACT FROM AUTHOR]

In this article we present a quantitative micromagnetic modeling analysis of thermally activated magnetic noise in spin valves heads at deep submicron track widths. It is found that, for these spin valve heads, the thermal magnetic noise is at a magnitude that is comparable to that of the head's Johnson noise. Reducing the sensor track width by keeping the same aspect ratio and film layer thickness will not necessarily yield an increase of thermal magnetic noise, which is attributed to the accompanying increase of the demagnetization field within the sensing layer. However, both the magnitude of noise and the noise spectra are strong functions of the sensor stripe height. An excessive stripe height will yield significantly higher thermal magnetic noise. [ABSTRACT FROM AUTHOR]

Significant enhancement of the interlayer coupling strength has been achieved by depositing Co nanolayers on both sides of the Ru layer in a conventional CoCrPt/Ru/CoCrPt antiferromagnetic interlayer exchange coupling structure. The interlayer coupling increases nearly linearly from 0.13 to 0.8 erg/cm² and then levels off with an increase in Co thickness. Substrate bias was found to be very harmful to the exchange coupling. The texture, structure and the growth of the grains and the crystal lattices were also studied with an x-ray diffractometer and a transmission electron microscope. [ABSTRACT FROM AUTHOR]

In this article, we present a combined analytical analysis along with micromagnetic simulations on the thermal stability of double layer longitudinal media with antiferromagnetic exchange coupling (AFC). The thermal stability enhancement in double layer AFC media is characterized quantitatively and comparisons with the performance of conventional single layer longitudinal media are made. It has been found that the thermal stability enhancement of the AFC media over a single layer media with the same medium coercivity can be achieved by optimizing the interlayer exchange coupling. The effective grain volume gain is found to be approximately V[sub 1] + 0.4V[sub 2], where V[sub 1] and V[sub 2] are the grain volumes of the top and bottom layers, respectively. Increasing V[sub 2] requires a larger interlayer exchange coupling constant. [ABSTRACT FROM AUTHOR]

A micromagnetic model for studying recording and noise characteristics in perpendicular media with a soft magnetic underlayer has been developed. The single pole head and soft magnetic underlayer are modeled with two-dimensional meshes and the medium is modeled with a three-dimensional granular structure. Utilizing the model, the dependence of recording characteristics on a medium microstructure, especially the intergranular exchange coupling, and write field is investigated. [ABSTRACT FROM AUTHOR]

Spacing fluctuations resulting from the head-tape interface dominate the metal-particle tape medium noise. Utilizing narrow-gap record heads, the spatial correlation of the head-medium interface has been completely and accurately characterized using a magnetic recording measurement. The measurements show that the spacing fluctuations damp with shorter wavelength, or in other words, the tape head-medium noise possesses a long spatial correlation length. In addition, the results demonstrate that the roughness-induced spacing fluctuations originate from portions of the tape surface that contact the tape, i.e., the load-bearing surface. This understanding of the head-medium noise reveals that the majority of the tape medium noise occurs during the recording process, and not during signal playback. Spatial correlation measurements on low-density (5 kfci) recordings provide verification of these conclusions. The study offers a thorough understanding of the surface roughness role on producing the head-medium noise. [ABSTRACT FROM AUTHOR]

A potential approach to extending current thin film media to 100 Gbits/in2 recording density is physical patterning of the media, perhaps via an etching technique. An advantage of patterning is the capability of creating advanced position error signal (PES) patterns that are difficult or impossible to generate with writing by a recording head. This study uses spin stand tester to investigate various PES patterns generated by a focused ion beam etching technique on conventional thin film disks. For all practical purposes, the patterned PES eliminates transition noise, track edge noise, and erase band, therefore, demonstrates a much better PES signal than conventionally written servo patterns. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This article presents a micromagnetic study of the dynamic magnetic switching process in the pole tip region of stitched-pole thin film write heads. The impacts of track width reduction and pole material saturation moment on the high frequency performance of the heads have been investigated. It is found that the magnetic switching process of the pole tip region at low recording frequencies can be characterized by three stages: the nucleation of a vortex (or vortices), followed by the motion of the vortex (or vortices), and finally the annihilation of the vortex (or vortices). At high frequencies, however, a residual vortex (or vortices) will always remain in the pole tips, resulting in lower head field amplitude. Frequency roll-off characteristics of the head field response have been calculated. The roll off is the result of residual vortex (or vortices), and the vortex moving speed limits the operational frequency range of the head. Reducing the track width lowers the head field 3 dB roll-off frequency. The simulation also finds that the use of 45/55 NiFe, which has significantly higher moment than permalloy, results in higher roll-off frequency as compared to permalloy. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Large scale 3D micromagnetic simulations are performed on single pole read heads with pole tip cross sections of 45×45 and 100×200 nm. It is shown that tips with these dimensions have a much higher output than predicted by an analytical theory using the reciprocity theorem. The larger of these tips still behaves in a relatively soft manner and has an output waveform shape very close to the one predicted by the analytical model. The response of the small tip however is hysteretic. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The presence of surface roughness in tape media results in a head-to-medium spacing that fluctuates throughout the recording process, which can have a large impact on the recording performance of the tape. To provide an understanding of the fluctuations introduced by the roughness, a self-consistent recording model combined with a micromagnetic MR readback module was used to study the recording (write) process on thin-layer metal-particle media with spatially correlated surface roughness. Correlation was made between the surface roughness and the recording characteristics through a spatial analysis of the recordings. Media with both long and short roughness correlation were investigated. Discussions on recording schemes that offer better immunity to the fluctuations introduced by the surface roughness are provided, and in particular the impact on write equalization is evaluated. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this article, a systematic micromagnetic analysis of the pseudospin valve magnetic random access memory device is presented. The article focuses on the correlation between switching field variation and geometric structure of the memory elements. For an elongated memory element with flat ends, magnetization reversal always initiates from the ends, yielding nonrepeatable switching processes and fluctuating switching fields. Tapering the element ends forces the reversal to start from the center region of the element and triggers robust repeatable magnetization rotation. However, sharp tips of the tapered ends are required, which may present limitations on fabrication in practice. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents an experimental study of the impact of the write wave form on high frequency magnetic recording. Experimental details; Results and discussions; Conclusions.

Investigates the effect of crystalline orientation and grain size on the switching behavior for patterned face-centered-cubic cobalt film elements. Correlation between film microstructure and magnetic switching properties; Model and energy analysis; Results and discussion.

Resulting from the curved thermal profile by near-field transducers, the transition curvature in heat-assisted magnetic recording is one of the critical factors significantly limiting the technology from achieving expected high area density capability. In this paper, we present a systematic micromagnetic modeling study to understand the underlying physics and to arrive at a solution that can correct the transition curvature for enhancing recording performance. Analysis show that the straightened transitions of the recording with the solution can yield a linear density increase of 50% at the same high track densities. [ABSTRACT FROM AUTHOR]

Presents a study that examined the effect of grain size dispersion on noise in longitudinal thin film recording media by micromagnetic modeling. Modeling in films with nonidentical grains; Results and discussion; Conclusions.

Presents a study which examined the reversal properties of isolated barium ferrite recording particles with cobalt-titanium substitution by using a magnetic force microscopy-based technique. Method used; Results and discussion; Conclusion.

Presents information on a study which modeled the magnetization domain structures in thin metallic films utilized as recording media using cellular automation on a two-dimensional triangular lattice. Computer simulation modeling of planar isotropic films; Results and discussion; Conclusions.

Presents a study which modeled edge noise in thin-film magnetic recording media using a planar array of hexagonal grains with long-range magnetostatic interactions as well as possible nearest-neigbor exchange interactions. Effects of exchange coupling on the ripple and vortex structures in the presence of the edge-field gradient; Fluctuation of the downtrack magnetization; Details of the magnetization configurations.

Presents information on a technique that changes a raw magnetic force microscopy (MFM) image into the magnetic pole density distribution without accurate knowledge of the tip magnetization orientation. Role of MFM in the imaging of magnetic structure in magnetic materials and devices; Procedure for obtaining the impulse response function of the MFM tip; Calculations on tip magnetization configuration.

Presents a micromagnetic study of magnetic switching properties on submicron scale single layer and multilayer thin film elements. Description of model and computation used; Co single layer film elements.

Reports that NiO/Ni81Fe19 bilayers with high exchange coupling and low coercivity were fabricated. Deposition of the bilayers onto a Si(100) wafer by changing the rf reactive sputtering conditions; X-ray spectra of three kinds of NiO/NiFe bilayers.